Originally Posted by Moccia

I have a 91 300zx n/a and I am having issues with it firing correctly. I thought it was a bad coil pack but after replacing it I found that in fact two of my cylinders wernt firing. When I first pulled coil packs looking for a dead coil pack I found what I thought to be the bad coil pack and replaced it, after starting it and not seeing any change I pulled it and the cylinder was still not firing, no reduced rpms, so I in turn starting pulling the other packs and as I got to the 2nd cylinder I pulled it to yet another no rshared_pm change, I can have both of these coil packs unplugged with no rshared_pm change. I dont know now if it is the coil pack connections that are bad (there is no corrosion on them) or if there is another factor as to why these cylinders arnt firing (bad injectors...idk) what tests can I do to figure out what is wrong? Ohm test the injectors which should read between 10-14ohms is what ive heard, any other suggestions? I also want to note that it starts and idles like this perfectly fine although rather high even when it heats up (around 1100) and when the A/c is turned on it goes lower (900rpms) and when turned off jumps up to 1500 before settling down, which im guessing might just be because of the two dead cylinders. Any suggestions would be great, thanks a lot.

Originally Posted by Sileighty_85

Its probably the Injectors, Early 300ZX's had a wiring issue with the ECU still giving the Inj constant power even when the car is off casuing the coils to die.

Might as well as replace all the injectors if thats the case.

http://www.jimwolftechnology.com/wol...INJFAILURE.pdf

Originally Posted by Petes s13

Ohm test your injectors with a multimeter, just like you posted. Make sure each injector is in between 10-14 ohms, what ever ones aren't are bad and need to be replaced. And pulling the plenum isn't as complicated as it sounds. It only takes roughly 30min to an hour. And your car is a 91, so most likely you have the PTU issue and need to contact Nissan to see if your car is under the recall for a new one. Also you might want to change your wiring harness to an updated efi harness or just get the updated Injectors with Pigtails. http://www.z1motorsports.com/index.php sells all of this. If your injectors aren't dead yet they probably will be.

Originally Posted by ZXTT

No he has a newer PTU

Joe just call me if you have my 495 number and we'll set up a time and I'll come by and look at it.....I got your note last Friday at the meet but so much shit happened that night i lost it. You'll need a DMM though cause I don't have one anymore. If you don't have my number let me know and I'll PM it to you, I don't have your number in my new phone so I can't call you.

Originally Posted by empire

my brother's z does that crap... for him, it was just the coil pack connectors... they wouldn't stay tight.
he also had an updated PTU or whatever it is called, and it was still bad. It caused all kinds of weird, random problems... he got lucky and nissan replaced it for him...

Originally Posted by moccia

Yeah, its a love/hate relationship right now, Im just surprised it still is semi drivable on 4 cylinders, that amazes me lol.

Originally Posted by empire

yeah, that is nissan for ya... My very first 240 ever ran on 2 cylinders and I had no idea...
when my brother's z would be dumb, it would drop anywhere from 1 to 3 cylinders.

Originally Posted by bullshit

blah blah blah

Originally Posted by moccia

Ummm yeah, if you read into this thread you'd notice that Dan is now coming to help me because of this post, and not to mention I dont have money to be buying a new car all the time as soon as it gets "old", If you dont want to give me a few pointers to try out in fixing this old car, then stay out of the thread? I was asking for correct ohms to begin with not "what is this thing that makes my car move", so I was looking for more technical responses than looking for an "internet mechanic". I also dont see what youre trying to do here, youre posting in a nissan/infinity technical forum about how I should stop crying about my car not driving...winner.

Originally Posted by RB20mike

ya any progress? My z32 does the same shit, it doesn't fire on cylinders 1 and 6 right now haha.

Originally Posted by Moccia

I'm waiting for dan to get back at me about coming over and giving me a hand but I'm going to ohm test them first thing in the morning, I've talked to a few people aboutthe issue that work on Z32s and they told me the early year 300's have injector problems which I guess they fixed from 1993 models on, so I'll post first thing tomorrow and if so start pulling my intake mani...

Originally Posted by Petes_s13

Here's a link to help you pull the plenum.
TwinTurbo.NET: Nissan 300ZX forum
You might as well remove the throttle body coolant lines while you have the plenum off.

And here's a helpful z32 FAQ's thread, basically gives you links to z32 DIY's stuff. Show's you how to do just about everything.
Z32 FAQ - Carolinanissans.com

Originally Posted by more bullshit

blah blah blah blah yadda yadda yadda

Originally Posted by Moccia

I think its a lost cause Empire, I've had my 300 for 5 years now and I love Nissan, I guess he took it the wrong way, anyway, I ohm tested all of my injectors today and im kind of confused...I got between 12.8-14 ohm readings on 5 of my injectors (I had to re-clean one of them which is no longer not firing) so im back to 5 cylinders, the puzzling thing is on the last cylinder I got no reading what so ever, I cleaned it for about 15min it looks like brand new contacts no green corrosion but still no reading, im guessing that means its just 100% dead? And for everyone having this similar problem my suggestion would be take your time and clean each injector as best as you can as well as the plug, and buy some contact cleaner, helped one of my cylinders...

Originally Posted by empire

yeah, if you aren't getting any reading at all, then the injector is totally done.

its awesome that cleaning that one fixed the problem.

I forget what the two plugs are called, but standing in front of the engine bay, front, left hand side, those two plugs (I believe they connect the engine harness to the chassis harness, I forget, its been a minute since I've been under the hood of a Z) take those apart and get them nice and clean since you've got the contact cleaner and all of that out.

Originally Posted by Moccia

So I have everything disconnected except the EGR...I cannot figure out for the life of me how to get under there and take it off >.< any help?

Originally Posted by Petes S13

It's on the bottom of the intake plenum on the sides. There's 2 tubes 1 under each throttle body, should have two 10mm bolts on each holding them onto the intake plenum.
I'd just remove the Egr since you have the plenum off, z1 sells a egr elimination kit for $33 bucks. http://www.z1motorsports.com/product...oducts_id=1875

Also I'd go ahead and remove the throttle body coolant lines too.
Here's the write up for that. http://tech.aus300zx.com/Rear_Water_...placement.html

Originally Posted by ZXTT

Joe my 2nd new clutch master should be delivered today, as soon as I install it I'll call you and come over.....Well, as long as some asshole doesn't steal it out of my mailbox again.

Originally Posted by Moccia

Damn, thats shitty, alright sounds good man, I have to write a damn paper for class, but after that im going to work on getting these coolant lines off and this dumb ass EGR and then work on replacing this Injector along with new fuel lines/vacuum lines, the problem im having with the EGR is that its right up against the plenum and the block, I can barely get anything in there to loosen it. And thank you Pete for those links, much appreciated.

Originally Posted by Moccia

Ordered the EGR elimitnation kit, but still looking for a 270cc injector! >.< Called Zdoc they wanted 125+tax...I can find them for 118 on Twintubro.net, any other suggestions on where to find one? Im fine with used...